Carburetor nozzle



2 Sheets-Sheet l H. A. BOLLER CARBURETOR NOZZLE June 20, 1950 Filed Jan. 27, 1947 INVENTOR. HENRY A. BOLLER ATTORNEY .Fune 20, 1950 H. A. BOLLER 2,512,085

CARBURETOR NOZZLE Filed Jan. 27, 1947 2 Sheets-Sheet 2 FUELS. AIR R-ATIO RATE OF AIR FLOW FIG.5.

INVENTOR HENRY A. BOLLER ATTORNEY Patented June 20, 1950 CABBURETOR NOZZLE Henry A. Boller, Pontiac, Mich., assignorito Car-' ter Carburetor Corporation, corporation of Delaware St. Louis-,. Mo.,.:a-

Application January 27, 1947, Serial No. 724.589

-1 Claim. 1.

This invention relates to carburetors for internal combustion engines and consists in novel means for supplying fuel thereto and, particularly, during periods of relatively low engine speed and air flow through the carburetor;

The simplest and most practical type of carburetor for internal combustion engines, particularly of the automotive type, utilizes the suction. produced by the engine to draw liquid fuel and air in the proper proportions into the engine intake manifold. However. a problem existsin. such carburetor in that insufficient liquid fuel is supplied. at periods of low engine speed and the consequent low air flo throughand suction within'the carburetor. Eiforts have been made to solve the problem by means of conventional air bleeds leading from a. zone of substantially atmospheric pressure to the, main fuel nozzle and metering valves or pins, with. stepped or tapered portions affecting the fuel metering orifice. the former case, the efiect of the bleed is noticeable throughout more of the range of engine speed than desirable and, in the. latter case, the effect is not substantial when low suctions are available. Additional fuel is desirable during periods of low engine speed and air flow'because such conditions exist either in the early part throttle range when the main nozzle is just: be-= ginning to discharge or, in the full throttle. range when the engine is subjected to a heavy load. Bothconditions demand the maximum liquid: fuel content in the mixture for smooth, strong operation.

It is an object of the present invention to provide means for enriching the fuel mixture supplied by the carburetor during periods of low engine speed and low air flow and suction within the carburetor.

Another object is to provide means for enriching the fuel mixture at such times only, the effect of the enriching means being inconsequential or absent at higher engine speeds and air flows through the carburetor.

Still another object is to provide the main fuel nozzle with a novel air bleed which functions at periods of low air flow through the carburetor to assist the discharge of fuel while becoming inconsequential at periods of higher air flows.

These objects and other more detailed objects hereafter appearing are attained by the device illustrated in the accompanying drawings in which:

Fig. 1 is a vertical section illustrating an internal combustion engine carburetor embodying the invention,

Fig. 2: is an enlarged'deta il ofFig. 1.

Fig. 3 is a View similar t'o Fig. 2,'but showing a modification. s v

Fig. 4 shows mixture quality curves illustrating the advantages of the present invention.

Fig; 5" is a'view of the detail in Figs. 2 and 3, but taken at thereto and illustrating another modification.

The carburetor in Fig. l comprises-a downdraft mixture conduit '5 having an air horn '6 at the) upper end controlled by aachoker'valve'l pro vided with a control arm '8. The lower end or" the conduitv is' flanged. as at 9' for attachment to the engine intake manifold ID. The dischargeof mixture from the carburetor is'controlled by" a butterfly throttle; valve. Ill mounted on shaft 12-. Intermediate to. choke and: throttle valves: therer is provided a series-of Venturi tubes I 3 carried by fin structure I311 and into the smallestventuridischarges main ifuel supply nozzle l4.

portion of the .constant:l-..'level chamber is: con-' trolled by the steppedlowerextremi-ty of a' metering; rod l8: connected joy-"pivoted lever l 9 and-link; 20 to an arm 2:! .rigid :with throttle shaft. [2. accelerating pump, as well known, may be provided if desired.

The mainfuel supply passes=-through an. upward-1y inclined fuelipassage 22 communicatingwith metering; orifice -elem'entcli'l and terminating.

in main nozzle l4. Fuel for idling is supplied through passages 23 and 24 terminating in ports 25 located adjacent and immediately posterior to the edge of throttle II when closed. The idling system is of the so-called interconnected type and includes restrictions 26 and 21 and an air bleed 28 for assisting in the proper functioning of the system.

As best shown in Fig. 2, main nozzle I4 extends approximately centrally through a downwardly and outwardly inclined recess 30 formed in the wall and fin structure of the mixture conduit and has a discharge outlet 3| within the Venturi tube and. spaced from the inner wall 32 thereof. This discharge outlet is preferably located within the middle or highest suction zone at the throat of the Venturi tube, although the exact position, disposition, and shape thereof may be varied in calibrating the carburetor. For instance, Fig. 3 shows a differently disposed outlet opening 3la of the main nozzle. Recess 30 terminates in an opening 33 flush with inner wall 32 of the primary Venturi tube. At its lower end, nozzle 14 has an annular shoulder 34 lodged against a shoulder within main mixture passage 22. The nozzle shoulder has a longitudinal port 35 which connects recess 30 with passage 22 and the interior of main nozzle I4.

This nozzle arrangement functions in the following manner: I

During periods of low engine speed and, consequently, low air flow and suction within mixture conduit 5, higher suction exists within the middle zone at the throat of the Venturi tube, to which nozzle outlet 3! is exposed, than exists at the wall of the Venturi tubeto which. air bleed recess opening 33 is exposed. Therefore, during such periods, air enters recess and port and joins the stream of fuel in the main nozzle in ever, at periods of higher air flow, this differential I of pressures within the Venturi tube and; particularly at the zones to which openings 3i and 33 are exposed, is substantially reduced and, ultimately, eliminated so that the air bleed is discontinued. 1

r'I'his situation is graphically illustrated in Fig. i in which solid linecurves' A and B represent the ratio of fuel to air in the mixture (the ordinates) for varying rates of air flow through the carburetor (the abscissae). Curve A is the part throttle curve-starting from the very rich'mixture-at dead idle atthe upper left-hand end of the curve and terminating in a sharply raising portion at the right-hand end which is produced by the metering pin. Curve B is the full throttle curve which starts with a lean mixture at the left-hand end and merges at its right hand end with the part throttle curve. The part throttle curve has a dip at A which is at the transfer point, that is, at that period when the main nozzle should start to discharge to provide the required fuel to air ratio and is, in part, due to the holding back effect of theidling system and the :weak suction to which the nozzle outlet is exposed. The. full throttle curve exhibits a weak or lean portion B which, similarly, results from the; weak suction available. By means of the novelair bleed arrangement illustrated and described, I am able to lift or enrich the portion A of the part throttle curve, as indicated in dotted lines at A and also to lift or enrich the weak portion B of the full throttle curve, as in ed by the dott d ine .3 S nce the'air bleed is effective only at the relatively low air flows, up to, say, 2 pounds per minute, these dotted line curves merge with the solid line curves early in the part and full throttle ranges. At part throttle, the effect of the air bleed is eliminated at a vehicle speed of approximately 30 miles per hour, while at full throttle the air bleed is no longer effective at approximately 10 miles per hour.

The exact shaping of the curve and calibration of the carburetor may be effected by varying the outlet opening of the main nozzle, one variation being shown in Fig. 3, and by varying the size, positioning, and number of the port connections between the air bleed recess and the main nozzle. In Fig. 3, a transverse port 35a is formed in the tubular portion of the main nozzle Ma. Also, the size and shape of recess 30 may be varied and,

.for instance, a single passage or slot 30a may be substituted, as shown in detail Fig. 5.

The invention may be modified in these and other respects as will occur to those skilled in the art and the exclusive use of all modifications as come within the scope of the appended claim is contemplated.

I claim:

In a carburetor, a constant level chamber, an induction conduit having a Venturi tube, a recess extending at an acute angle downwardly and outwardly from an opening through and flush with the inner wall of said Venturi tube through the wall structure of said conduit, and a main fuel nozzle extending upwardly from said chamber through said recess and having a discharge outlet located substantially within the central zone of said Venturi tube, there being a passage forming clearance within said recess along said nozzle and porting connecting said nozzle substantially below the normal fuel level and said recess for introducing air from said recess into the fuel stream in said nozzle. f

' HENRY A. BOLLER.

REFERENCES CITED The following references are of record in thefile of this patent:

UNITED STATES PATENTS Number Name Date 1,916,062 Memini June 27, 1933 1,929,266 Viel Oct. 3, 1933 1,976,452 Mock Oct. 9, 1933 2,255,296 Moseley Sept. 9, 1941 2,407,534; Carlson Sept. 10, 1946 

